Project 1 will focus on two primary goals. The first concerns the cognitive changes that occur with age and their relationship to neuroanatomic and neurophysiologic changes in the brain. Toward this end data from 200 optimally healthy subjects (approximately 100 males and 100 females) will be examined. Most of these data will have been gathered in previous funding periods, however, some data will be gathered in the next funding period in order to permit state-of-the art MRI analyses. A variety of statistical techniques will be employed to evaluate age-related change. The second primary goal of Project 1 concerns dementia of the Alzheimer type (AD). One hundred and twenty five questionable cases of AD (CDR=0.5) and forty normal controls (CDR=0) will be followed for a minimum of 3 years. It is anticipated that approximately 2/3 of the questionable cases (n=80) will be categorized as AD by the end of the follow-up period. This will permit an examination o the cognitive differences between questionable cases who are diagnosed as AD on follow-up and questionable cases who are not. It will also permit the evaluation of the relationship between cognitive test scores and quantified measures of brain structure and function (i.e., qEEG, MRI, SPECT) in these very mildly impaired patients.